In, for example, U.S. Pat. No. 3,921,049, issued to G. Mellors et al. on Nov. 18, 1975, a photovoltaic assembly for charging a battery is described. The photovoltaic assembly is simply connected to the battery to be charged with a diode between them. This diode prevents reverse current flow when the photovoltaic assembly is not subjected to sufficient light intensity for the photovoltaic assembly output voltage to be greater than the battery voltage plus the diode forward voltage.
While the device of G Mellors et al. is useful, any light intensity to which the photovoltaic assembly is subjected, which can not generate a voltage greater than the combined voltage of the battery and the diode, will not activate the photovoltaic assembly to output a charge current. As a result, power outputs at these light intensities are not utilized. This situation worsens as the battery voltage increases as it is being charged.
There is a need for a photovoltaic assembly power output-utilizing device which utilizes, more effectively, available light. In particular, a photovoltaic assembly is desired which outputs over a wide range of light intensity to which the photovoltaic assembly is subjected.
In U.S. Pat. No. 6,367,259, issued to M. Timm on Apr. 9, 2002, it has also been proposed to accumulate electrical energy from a photovoltaic assembly through a capacitor and a control circuit, and then directly discharge the capacitor to, for example, an electric motor once there is enough energy accumulated in the capacitor to run the electric motor.
While the device described in the Timm patent is useful, the range of the voltages in which the capacitor is discharged determines the power output from the photovoltaic assembly, and the operating voltage range of the electric motor determines this range.
This range of voltages will not provide the greatest power output that the photovoltaic assembly is capable of providing.
There is a need for a photovoltaic power output-utilizing device, which will obtain the greatest possible output of energy from the photovoltaic assembly in at least one output voltage range.